Diocese in Tuscany. The city stands on a rocky mountain 1770 feet above the sea level, between the rivers Bra and Cecina, and is surrounded by strong walls. The cathedral, consecrated by Callistus II in 1120, was enlarged by Andrea Pisano in 1254, and again in 1576. The high altar is adorned with sculpture by Mino da Fiesole; among the pictures is an "Annunciation" by Luca Signorelli, and there are pictures by Benvenuto di Giovanni, Leonardo da Pistoia, and others. In the baptistery (1283) are a font by Sansovino and a ciborium by Mino da Fiesole. Other churches are those of S. Lino (1480) and S. Francesco. In the Palazzo Publico (1217) are the archives of the city. The Palazzo Tagani contains an important museum of Etruscan and Roman antiquities. In the middle of the city rises the citadel, built in 1343 by the Duke of Athens and enlarged by the Florentines. Remains of the ancient surrounding walls (the Portadell' Arco) may be seen in the neighbourhood, as also of baths, of an aqueduct, an amphitheatre, and, above all, of several Etruscan burial places. The district is rich in alabaster, the working of which is the chief industry of the city, and in mineral waters, such as those of S. Felice and the Moie, or salt springs. Still more important are the Soffoni of Larderello, from which is obtained boric acid (exported for the most part to England), the sulphur lake of Monterotondo, the copper springs of Caporciano, and the baths of Montecatini.

In the Etruscan epoch Volterra, called Felathri by the Etruscans and Volaterrae by the Romans, was one of the most important cities in the Etruscan Confederation. From the period of the kings it was at war with Rome. In 298 B.C., when he became consul, Scipio gained a victory here over the Etruscan armies. In the Punic Wars, however, the city was allied with Rome. In 80 B.C. it was taken by Sulla, after a siege of two years. In the succeeding centuries it was of some importance in the Gothic War. In the Carlovingian period it belonged to the Marquisate of Tuscany; with the approval of Henry, son of Barbarossa, the government of it afterwards passed into the hands of the bishop, until his temporal authority was suspended by the commune. In the wars or factions of the thirteenth century, Volterra, being Ghibelline, was continually embroiled with the Florentines, who captured it in 1254, but obtained definitive possession of it only in 1361. In 1472 it attempted a rebellion against Florence but without success, and was then deprived of many of its rights. It was the native city of the poet Persius Flaccus, of the humanists Tommaso Inghirami and Raffaele Maffei, of the painters and sculptors Baldassare Perugini and Daniele Ricciarelli. According to the "Liber Pontificalis", Volterra was the birthplace of St. Linus, the immediate successor of St. Peter. Nothing is known as to its Christian origins; Eucharistus, the first bishop of Volterra of whom there is any record (495), was deposed by the pope, and Helpidius (496) was put in his place. Justus (560) was at first involved in the Schism of the Three Chapters. Other bishops were: Gunfridus (1014), whose metrical epitaph is to be seen in the cathedral; Herimannus (1066), a Camaldolese monk and reformer of the clergy; Galgano, killed by the people in 1172, for some unknown reason; St. Ugo dei Conti del Castel d'Agnato (1173 84), a defender of the rights of his church, and founder of a college for the education of clerics; Pagao dell'Ardenghesca (1213), who vainly endeavoured to retain the temporal government of the city. The conflict on this score was continued under Pagano's successors, particularly under Raineri Belforti (1301). Roberto degli Adimari was deposed for taking part in the Council of Basle. Joseph du Mesnil (1748) died a prisoner in Castel Sant' Angelo. Giuseppe Incontri (1806) distingished himself by his beneficence. Pius IX made his first studies in the Piarist College at Volterra.

Volterra was immediately subject to the Holy See until 1856, when it became a suffragan of Pisa. The diocese contains 111 parishes with 99,900 souls; 206 priests, secular and regula; 6 houses of male religious and 12 of Sisters; one school for boys, and 2 colleges for girls.